Differential scanning calorimetry (DSC) is a thermoanalytical technique that measures heat generated or required in thermally active processes as the temperature of a sample is varied. When applied to biochemical systems, DSC can provide a label-free method to determine the thermodynamic properties of a wide variety of biomolecular interactions and conformational transition. DSC instruments, however, can be cumbersome and require large sample consumption, which has hindered the widespread application of DSC to biomolecular characterization.
Microelectromechanical Systems (MEMS) are small integrated devices or systems that combine electrical and mechanical components in very small mechanical devices. MEMS technology is based on fabrication technologies that can realize miniaturization, multiplicity, and microelectronics.
Some currently available MEMS calorimeters provide solid- or gas-phase or droplet-based detections. However, it can be difficult to properly handle liquid samples in a well-defined environment in the currently available MEMS calorimeters.
Flow-through and continuous-flow MEMS calorimeters integrate microfluidic chambers or channels as biological reactors. These devices can provide controlled fluidic environments and can allow easy integration with other microfluidic functionalities or thermal sensing configurations for biochemical thermodynamic investigations. However, these devices can still require a large amount of samples while being limited by significant convective heat leakage due to the continuous flow.
In addition, calibrating existing MEMS DSC devices can be complicated due to a lack of integrated heating elements and temperature sensing. Temperature-modulated calorimetry (AC calorimetry) involves calorimetric measurements under small temporally periodic temperature variations. Such temperature modulation can allow thermal relaxation of biomolecules, and thus AC calorimetry can detect biomolecular interactions under quasi-equilibrium conditions, and allow the biochemical reaction signal to be extracted at the modulation frequency in the face of broad-band background noise. However, these chips can involve thin solid films and operating parameters which are not suitable for biomolecular characterization in solution phase.
Isothermal titration calorimetry (ITC) can measure heat generated or required for a biochemical reaction as a function of the molar reactant ratio, and has been used in applications such as drug discovery and biotherapeutic development. However, conventional ITC instruments can have complicated structural designs, slow thermal response, and large sample and reagent consumption.